Plaster base



Aug. 31, 1937. A. ELMENDORF PLASTER BASE Filed May 16, 1955 their thickness.

Patented Aug. 31, 1937 UNITED STATES PATENT OFFICE 11 Claims.

For many purposes it is desirable or necessary to employ a foundation or base of wood to support plaster for a wall or ceiling. The only form in which wood is now available for this use is that of the standard wood lath. Long experience has demonstrated that such laths should be about three-eighths of an inch thick and about one and five-eighths wide, and that they be spaced apart from each other a distance about equal to Each such lath must be nailed individually to the studding, so that the labor cost of applying the laths is considerable. Furthermore, since the laths become very wet at the time of applying the plaster thereto, they are apt to 115 twist and warp, and in any event, the shrinkage across the widths thereof, in drying, produces internal stresses in the plaster which frequently cause cracks extending in the direction of the lengths of the laths. Also, when the base or foundation, with its facing of plaster is exposed to temperatures which are much higher on one side thereof than on the other as, for example, in an ordinary plastered wall of a room, the temperature in the layer of plaster may vary greatly at different points. If the wall be an outside wall, there may be very cold air in contact with the outer faces of the laths and with the keys of plaster extending between the laths, while the inner or plaster face of the wall is exposed to warm air. The laths act as insulators which protect against the cold those areas of plaster directly overlying the same. However, those portions of the plaster constituting the keys and those parts of the main layer of plaster registering with the keys, are not protected and heat will be withdrawn rapidly. For this reason in the winter there is a very great difference in temperature in the layer of plaster between the lines comprising the longitudinal center lines of the laths and the gaps or spaces between the laths. One effect of this difference in temperature is that in time the dust collects to such an extent along the lines of the keys as to give rise to distinct dark bands.

The object of the present invention is to produce a foundation or base for plaster comprising or composed mainly of wood, which shall possess all of the advantages of the ordinary wood laths and be free from the disadvantages or objections which I have pointed out as incident to the use of such wood laths.

A further object of the present invention is to produce a simple and'novel material composed entirely or largely of wood, which may be applied in its position of final use in the form of sheets.

In carrying out my invention I employ narrow strips of wood, of such cross-sectional areas that they have only the necessary stiffness, and tie these strips together with elements adapted to be embedded in the plaster to reinforce the latter in the direction of shrinkage of the Wood in the stiff or rigid strips. Employing narrow strips instead of wide laths, the shrinkage ina-ny individual strip parallel to the plane of the plaster layer is small compared to the shrinkage in the wide lathyand therefore the shrinkage stresses that tend to produce cracks inthe plaster are so small that there is little danger of creating cracks. At the same time, the plaster is reinforced to resist the shrinkage stresses in the strips and, therefore, the danger of causing cracks in the plaster due to shrinkage or other distortion in the wood base is, for all practical purposes, eliminated. Furthermore, because the strips of wood are narrow, the

curve representing temperature in the plasten,

along the line extending cross-wise of a series of laths or strips is more nearly astraight line than is the case where the old, standard lath foundation is employed, and the objection due to the comparatively widejtemperature differences under the old practices are avoided.

The combined tie and reinforcing devices are preferably flat, ribbon-like strips which may be wood veneer, thick, tough paper, or even metal. Such tie means may therefore be sufficiently flexible to permit large foundation sheets to be rolled up. Therefore viewed in one of its aspects, my invention may be said to have for its object to produce a foundation or base for plaster, comprising or composed mainly of wood, which shall be in sheet form and which may be rolled up for transportation or handling.

My improved foundation or base does not require that the plaster ooze out through the back to form large overhanging lips on the keys, as there is effective interlocking between the plaster and the tie elements of the foundation or base. For this reason my improved material is well adapted tobe backed with sheets that will serve as insulation, waterproofing or both. In one emcrosses.

its objects and advantages, reference may be had to the following detailed description taken in connection with the accompanying drawing, wherein:

Figure 1 is a more or less diagrammatic view showing a fragment of a wall comprising plaster on an ordinary wood lath base, with a curve indicating temperature variations in the plaster along a line transverse to the laths; Fig. 2 is a view similar to Fig. 1, illustrating my improved foundation or base, however; Fig. 3 is a plan view of a panel or sheet of my improved material; Fig. 4 is an edge view of the panel or sheet of Fig. 3; and Fig. 5 is a perspective View of a fragment of a panel or sheet having a backingthereon. I

Referring to Fig. 1 of the drawing A, A represent ordinary wood laths and B a layer of plaster overlying the same and keyed thereto in the usual way. C is a temperature curve, assuming that the air is colder on the lathside than on the other; the difference in length of the ordinates from the surface of the plaster to this. curve representing differences in temperatures along a line extending transverse to the length of the laths. In Fig. 2 the plaster is shown as applied over narrow strips I, in accordance with the present invention. The temperature curve D, assuming the same temperature conditions as in Fig. 1 is not far from a straight line, there being but little difference in the length of the ordinates from various points along this curve to the surface of the plaster.

The wood strips I, may be of any desired 5 cross-sectional shapes and areas as long as they are quite narrow as compared to ordinary lath. i I have found that strips of about the same thickness as ordinary wood laths, and approximately square in cross section give satisfactory results. 40 The strips are preferably spaced apart about the same distance as is customary in the case of standard wood laths. In this arrangement, consequently, the spaces between the Strips are approximately equal to the widths of the strips. 45 Any desired number of strips, of any desired length, are united by suitable tie membersto form a panel or sheet which may be nailed any place as a single unit. The tie means take the form of thin, narrow strips 2 which overlie the 5 strips I on the side or face over which plaster is to be spread. These tie elements are preferably arranged at right angles to the strips and, while spaced apart from each other, are preferably close enough together to constitute effec- 55 tive reinforcement for the plaster cross-wise of the strips I. The tie elements may be composed of thin strong wood veneer; although for some purposes they may be formed of thick, tough paper, or even of metal. Since the tie elements 60 are to reinforce the plaster the wood of which they are composed, when made of wood, should be of a kind possessing great tensile strength. Each tie element may be stitched, nailed or otherwise fastened to each of the strips which it In the arrangement shown,"the ribbon like tie elements are held to the rigid strips by light staples 3, each wide enough to completely span the width of a tie element.

The ribbon-like tie elements are preferably flexible so that a sheet or panel may be rolled up. In fact, since these elements will ordinarily not have a thickness in excess of about one thirty-second of an inch, they will'naturally be flexible. When the tie elements are of wood 75 or paper a workman can readily cut a sheet or panel in two, or cut it to any required shape, without any other tool than a hatchet.

The rigid strips may be cut away on their front faces at one end and on their rear faces at the other end, as indicated at 4 and 5, so that scarf 5 joints may be made between panels or sheets placed end to end.

In some instances a sheet or panel may be provided with a suitable flexible backing. Thus, in Fig. 5 there is a backing sheet 6 of paper, or 10 other suitable material, which may be coated on one side with asphalt or the like, as indicated at 1, to provide waterproofing and also to cause the sheet to adhere to the back faces of the rigid strips. The other or opposite face of the sheet 15 6 may have thereon a layer 8 of suitable material to give to it the capacity of efficiently refleeting heat. A wall plastered over a foundation or base of this kind is efiectively insulated and is also impervious to moisture which might 20 otherwise come in from the outside.

My improved foundation or base may be made in sheets of any desired size and shape. Perhaps a most practical size is one presenting one yard of plaster-receiving surface. Since lathersl' 25 are paid by the square yard of lathing, one need only to count the number of panels that he has applied, if each panel covers one yard, to ascertain his yardage. The labor cost of applying my plaster base is obviously small compared '30 with that of applying laths, one at a time.

When plaster is applied to my foundation or base, the combined ties and reenforcing strips or ribbons extend through the keys between the rigid strips and thus lock the plaster securely to the foundation or base. Consequently it becomes unnecessary to work the plaster until large masses l break off behind the base or foundation and are wasted, as is usual with ordinary lath, in order to insure a good interlock for the plaster. If then-40 shrinking of the narrow rigid strips were otherwise sufiicient to set up in the plaster stresses that might result in cracks, the presence of the reenforcing tension members embedded in the plaster would effectually prevent cracking, so thatx the plaster is free from a danger which is always present where standard wood laths are used. So, also the comparatively wide differences in temperature between different points in the surface of the plaster, a common fault in standard lath foundation, is, if not completely eliminated, at least rendered a negligible factor.

While I have illustrated and described with particularity only a single preferred form of my invention, with a few modifications, I do not de-w'55 sire to be limited to the exact structural details thus illustrated and described; but intend to cover all forms and arrangements which come within the definitions of my invention constituting the appended claims.

I claim:

1. A sheet or panel-like material adapted for use as a plaster base, comprising stiff, narrow ficiently close relation to each other to lock the plaster securely to the sheet or panel.

2. A sheet or panel-like material adapted for use as a plaster base, comprising stiff, narrow" strips of wood spaced apart from each other, and thin, straight, flat strips of wood extending crosswise of and fastened to the aforesaid strips; the flexible strips lying flat on the face of the sheet to which the plaster is to be applied and being so spaced that they will extend through the plaster keys in sufficiently close relation to each other to lock the plaster securely to the sheet or panel.

3. A sheet adapted for use as a plaster base, comprising stiff, narrow strips of wood spaced apart from each other, and spaced, straight, flat strips of tough flexible material extending crosswise over and fastened to the aforesaid strips, the ends of the first mentioned strips being beveled to permit scarf joints to be made between two sheets placed beside each other.

4. A sheet or panel-like material adapted for use as a plaster base, comprising stiff, narrow strips of wood spaced apart far enough from each other to permit wet plaster to flow readily between them, and thin, straight, flat, spaced strips of tough paper extending crosswise of and fastened to the aforesaid strips; the flexible strips lying flat on the face of the sheet to which the plaster is to be applied and being so spaced that they will extend through the plaster keys in sufficiently close relation to each other to lock the plaster securely to the sheet or panel.

5. A sheet or panel-like material adapted for use as a plaster base, comprising stiff, narrow strips of wood spaced apart from each other, and thin, straight, flat, spaced, flexible metal extending crosswise of and fastened to the aforesaid strips; the flexible strips lying flat on the face of the sheet to which the plaster is to be applied and being so spaced that they will extend through the plaster keys in sufiiciently close relation to each other to lock the plaster securely to the sheet or panel.

6. A sheet adapted for use as a plaster base, comprising stiff, narrow strips of wood about as wide and as thick as the thickness of a standard wood lath spaced apart from each other, and spaced, flat strips of tough flexible material extending crosswise over and fastened to the aforesaid strips; the flexible strips lying flat on the face of the sheet to which the plaster is to be applied and being so spaced that they will extend through the plaster keys in sufliciently close relation to each other to lock the plaster securely to the sheet or panel.

'7. A sheet or panel-like material adapted for use as a plaster base, comprising two sets of parallel, spaced straight narrow strips arranged crosswise of each other and fastened together, the strips of one set being of wood about as wide and as thick as the thickness of a standard wood lath and having between them spacings about equal to their width, and the strips of the other set being thin, flat, and flexible; the flexible strips lying flat on the face of the sheet to which the plaster is to be applied and being so spaced that they will extend through the plaster keys insufficiently close relation to each other to lock the plaster securely to the sheet or panel.

8. A sheet or panel-like material adapted for use as a plaster base, comprising two sets of parallel, spaced straight narrow strips arranged crosswise of each other and fastened together, the strips of one set being stiff and those of the other set being thin, flat and flexible, and a backing sheet covering the structure on the side opposite that on which the flexible strips are located; the flexible strips lying flat on the face of the sheet to which the plaster is to be applied and being so spaced that they will extend through the plaster keys in sufliciently close relation to each other to lock the plaster securely to the sheet or panel.

9. A sheet or panel-like material adapted for use as a plaster base, comprising two sets of parallel, spaced narrow strips arranged crosswise of each other and fastened together, the strips of one set being stiff and those of the other set being thin, flat and flexible, and a backing sheet covering the structure on the side opposite that on which the flexible strips are located, said backing sheet having on the inner face an adhesive material securing it to the stiff strips and having on the outer face a heat-reflecting surface; the flexible strips lying flat on the face of the sheet to which the plaster is to be applied and being so spaced that they will extend through the plaster keys in sufficiently close relation to each other to lock the plaster securely to the sheet or panel.

10. A sheet or panel-like material adapted for use as a plaster base comprising stiff strips of wood spaced apart from each other to about the same extent as the spacing of ordinary wooden laths, the width of such strips being about the same as the distance between adjacent strips, and thin, flat flexible strips extending crosswise of and fastened to the aforesaid strips, the width of each flexible strip being many times as great as its thickness, and the flexible strips lying flat on that face of the panel to which the plaster is to be applied and being so spaced that they may extend through the plaster keys close enough to gether to hold the plaster securely to the panel.

11. A sheet or panel-like material adapted for use as a plaster base, comprising stiff, narrow strips of wood spaced apart from each other, and thin, flat flexible strips extending crosswise of and fastened to the aforesaid strips on that side of the panel to which the plaster is to be applied, the stiff strips being spaced apart far enough to permit the plaster to flow readily underneath or behind the flexible strips, and the flexible strips being so spaced that they may extend through the plaster keys close enough to gether to lock the plaster securely to the panel.

ARMIN ELMENDORF. 

